Odor Quantification MSW

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Odor Quantification Methods &

Practices at MSW Landfills

Authored by:

Charles M. McGinley, P.E.

St. Croix Sensory, Inc.

Michael A. McGinley, MHS

McGinley Associates, P.A.

Proceedings of

Air and Waste Management Association

91st Annual Meeting and Exhibition

San Diego, CA: 14-18 June 1998

St. Croix Sensory Inc. / McGinley Associates, P.A.

13701 - 30th Street Circle North

Stillwater, MN 55082 U.S.A.

800-879-9231

[email protected]

Copyright 1998


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ABSTRACTThe measurement of odors from municipal solid waste (MSW) landfills is usually a requirement

for compliance monitoring, planning, site expansion and review of operational practices.

Additional purposes for quantification of MSW landfill odors include trials and testing of topical

and area dispersed odor counteractant sprays and other alternative practices.

Sources of odorous emissions are a challenge to control by MSW landfill management. When

odors impact the surrounding community, regulators attempt to enforce compliance. Emission

sources, that include hauling trucks, specific odorous materials (i.e. sludge), landfill gas, cell

cover breaches and other on-site activities, are difficult to identify and to compare on a relative

basis. Presenting the greatest challenge for odor control is the open working face of the MSW

landfill.Portable and laboratory gas monitoring sometimes lead to identifying an odorous source because

of the chemical differences between the emissions. However, because of the many potential

odorous sources and their chemical similarities or complexities, odor measurement is the direct

way to compare and quantify the various source contributions. After all, it is the odors that

impact the community. Specific odorous emissions can be collected from surfaces and from the

ambient air. These samples, shipped to an odor laboratory, can be evaluated for odor

concentration and odor quality (i.e. descriptors). However, many of the odors occurring at

MSW landfills can not be collected for laboratory odor evaluation.

Field observation by operators, inspectors and citizens provide a cost effective means to quantify

odors from MSW landfills. Using simple word intensity scales or butanol intensity scales withstandard odor descriptor nomenclature, direct field observation is a dependable practice for

quantification of odors from MSW landfills.

This paper presents specific methods and practices for quantification of odors from MSW landfills

by regulators, operators and the community for purposes of monitoring, planning and testing.

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INTRODUCTION

Communities and regulators readily know that municipal solid waste (MSW) landfill operations

yield odorous emissions. MSW landfills can emit odors in varying degrees from many potential

sources that may include1:

1)

Arriving and queuing hauling trucks2) On-site vehicles and heavy equipment

3) Biodegraded household waste

4) Sewage sludge

5) Working face

6) Fugitive odorous dust

7) Temporary cover

8) Capped cells

9)

Access road construction

10) Leachate collection systems

11) Leachate treatment systems

12)

Monitoring wells

13) Gas well construction

14) Gas wells and collection piping

15) Gas treatment systems

16)

Gas flares17) Associated landfill activities, ie. yard waste and composting.

18) Adjacent unrelated landfill activities and businesses

Each of these potential odorous sources varies in the following ways:

emission type (surface or point source)

emission rate (odor units per second)

odor strength (concentration and intensity)

odor persistence (dose-response relationship)

odor character (descriptors and Hedonic Tone)

frequency of occurrence (random or repeating)

duration of emission (episode or activity related)

circumstances (temporary condition, emergency release, construction, etc.).

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Quantification of odors from MSW landfills is typically prescribed for the following purposes:

1. Compliance monitoring (compliance assurance)

2. Determination of compliance (permit renewal)

3. Determination of status (base line data for expansion planning)

4. Determination of specific odor sources (investigation of complaints)

5. Verification of complaints (notice of violation)

6. Monitoring daily operations (management performance evaluation)

7. Comparison of operating practices (evaluating alternatives)

8. Monitoring specific events or episodes (defensible credible evidence)

9. Determination of an odor counteractants efficacy (scientific testing)

10. Determination of an odor counteractants cost effectiveness (cost minimization)11. Comparison of odor counteractants and other methods (cost accountability)

12. Verification of odor dispersion modeling (model calibration)

Each of these purposes dictates a need for dependable and reproducible methods and practices for

odor quantification. The trend in the United States and internationally is toward a recognition

that odor is a legitimate air pollutant and odor can be controlled. Therefore, regulators and

operators of MSW landfills are faced with practical needs for odor quantification, whether the

purpose is solely for complaint investigation (i.e. public relations) or for permit renewal (i.e.

facility survival).

The methods of odor quantification address the purpose of the work (i.e. site specific criteria).The practicesof odor quantification address the scientific procedures (i.e. ASTM Standard

Practices). For example, a MSW landfill may need to conduct routine odor monitoring because of

a permit condition. The purpose of the odor quantification demands a method that will satisfy the

permit conditions. The method that would be selected might be a schedule of routine odor

observations at specific locations around the property line and within the community. In this

example, the odor quantificationpracticethat would be selected might be the use of ASTM E544

(1988), Standard Practice for Referencing Suprathreshold Odor Intensity.

Site specific conditions often place significant limitations on the ability of regulators and MSW

landfill operators to implement a program of odor quantification. Local terrain and local

meteorology are common constrains that challenge method development and sometimes limit the

choices of odor quantification practices.

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METHODOLOGIES

Ten methods are commonly used by MSW landfills and regulators responsible for permitting. The

term protocolis often applied to the method that is selected for a specific program or

requirement. The following methods or protocols are presented in brief exemplary form as a

guide.

(1) Point Source Sampling- The operations on a MSW landfill site may include leachate

treatment, gas cleaning, enclosed transfer operations or other buildings or processes that have

a specific point emission source. The point source may be a stack, roof exhaust or building

side vent. The sampling of the potentially odorous point sources involves the collection of the

air from the point source in a Tedlar gas sample bag using a vacuum chamber, sometimes

called a sampling lung2. The bag is placed in the vacuum chamber with a Teflon tubing line

placed in the exhaust stream. A pump is used to create a vacuum in the chamber, which

causes the odorous air sample to flow into the bag. The bag is first partially filled, then

emptied and finally filled with the sample. This method, called conditioning the bag, is

believed to minimize the loss of odor on the bags inside surface. The odorous air sample is

express shipped to an odor laboratory for evaluation of the odor parameters, ie. odorconcentration and descriptors.

(2) Surface Sampling- A MSW landfill contains a number of surfaces that have the potential to

emit odorous gases, i.e. daily cover, temporary cover or capped cells. The collection of odors

from surfaces requires the use of a device called a flux hood3. A simple flux hood is a bowl

inverted on to the surface that is to be sampled. Odor free air is supplied to the flux hood

during sampling from the flux hood. Several methods of surface sampling have been used by

investigators. One alternative method utilizes a portable wind tunnel4. Any of these methods

are available for use at a MSW landfill and the choice will be dictated by the site specific

conditions and the data requirement needs.

(3) On-Site Monitoring- Operators have the unique ability to monitor odors throughout theday. Operator monitoring can include odor observations of arriving materials (i.e. sludge),

the working face, the leachate collection system and the gas wells. Monitoring on-site can

also involve odor observations from selected predetermined locations. Sample locations

might be at and around the working face, on closed cells and adjacent to leachate systems.

(4) Complaint Response- The use of Odor Complaint Hot Lines is a common method used by

MSW landfills and communities. A Hot Line phone system provides citizens with direct

access to register a complaint and other relevant information. A complaint response plan,

with designated on call inspectors, produces opportunities for observing odor episodes and

for tracking odors to the contributing sources.

(5) Random Monitoring- A frequently used method for odor monitoring is the randominspection approach. This method is also called the unannounced inspection. The random

monitoring method leads to a compilation of data that can be correlated with meteorological

information and on-site activities. Regulators often find that random monitoring is the only

cost effective method available for compliance determination.

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(6) Scheduled Monitoring- Well planned scheduled monitoring can be limited to a daily drive

around the MSW landfill site or a daily visit to several predetermined monitoring locations.

The data from scheduled monitoring can be used to correlate the many parameters which

potentially influence odor episodes. Meteorological conditions and on-site operating activities

need to be recorded during the monitoring. The use of a versatile data base will facilitate the

analysis of the data.(7) Citizen Monitoring- The implementation of citizen monitoring can be part of an interactive

community outreach program for a MSW landfill. The primary function of citizen monitoring

is to obtain information, through accurate record keeping, that represents real conditions in

the residential community. The citizens recruited would be trained to measure odors using an

intensity scale and to assign standard odor descriptors. The citizen monitors can assist in

determining prevalent times which odors occurs and prevalent weather conditions of odor

episodes. Citizen monitors also help in understanding the odor intensity level at which an

odor is considered a nuisance (i.e. first becomes a nuisance).

(8) Citizen Jury- Occasionally a citizen jury is impaneled to evaluate odors associated with a

MSW landfill. A typical citizen jury would be gathered to observe odors at specific locationsand asked to respond to the following question with a YES or NO: In your opinion, do the

odors witnessed at this location on this day and at this time have the intensity and character

which would interfere with the normal conduct of business or cause material, physical

discomfort to a person ?

(9) Intensive Odor Survey- An in-depth evaluation of on-site odor generation and off-site odor

impact might be needed for a MSW landfill in preparation for a permit review or facility

expansion. Extensive data collection of odors, related meteorological conditions and site

operations will identify which sources and operations cause odors and which ones that do not

cause odors. All potential odor sources can be ranked and their relative odor contributions

determined. Short term trials of odor counteractants also may require an intensive period ofdata collection using odor monitoring practices.

(10) Plume Profiling- Odor dispersion monitoring can be supplemented with odor plume

profiling. Several inspectors spaced cross wind and down wind from the odor source can be

assigned to measure odor intensity. Multiple plume profiles, during differing wind conditions,

can be used to calibrate a dispersion model or verify model predictions.

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Suprathreshold Odor Intensity

Odor intensity quantification can be accomplished using an Odor Intensity Referencing Scale6

(OIRS). Odor intensity referencing compares the odor in the ambient air to the odor intensity of a

series of concentrations of a reference odorant. A common reference odorant is n-butanol. The

inspector, investigator, monitor or operator observes the odor in the ambient air and compares it

to the OIRS7. The person making the observation must use a carbon filtered mask to refreshtheir olfactory sense between observations (sniffing). Without the use of a carbon filtered mask

the observers olfactory sense would become fatigued or would adapt to the odors in the

surrounding ambient air.

Using the OIRS, the intensity of the observed air is expressed in parts per million of n-butanol.

A larger value of butanol means a stronger odor. The OIRS serves as a standard practice to

quantify the intensity of odors for documentation and comparison purposes.

Odor Threshold Concentration

The odor concentration is a number derived from a laboratory dilution of a sample odor8.

Dilution of the odor is the physical process that occurs in the atmosphere down wind of the odorgenerating source. The receptor (citizen in the community) sniffs the diluted odor. The dilution

ratio is an estimate of the number of dilutions needed to make the odor non-detectable

(threshold).

Samples of ambient air that have been collected on-site and surrounding a MSW landfill can be

evaluated at an odor laboratory using trained panelists (assessors). The odor panelists observe the

sample using an instrument called an olfactometer. The testing procedure produces threshold

values that are called detection threshold and recognition threshold. The detection threshold

represents the dilution ratio needed to make the sample detection free. The recognition

threshold represents the dilution ratio needed to make the sample odor free. The differences

between the detection threshold and recognition threshold may only be significant in odor

dispersion modeling. However, when comparing sample results, one type of threshold must be

used consistently.

In addition to the determination of odor thresholds, an odor laboratory can conduct evaluations

for the following odor parameters:

Odor Intensity using the n-butanol Odor Intensity Referencing Scale

Odor Quality using Standard Character Descriptors

Odor Hedonic Tone (Pleasantness verses Unpleasantness)

Odor Persistency (Dose-Response)

A field procedure exists, known as the Scentometer, for the estimating of ambient odor

threshold9. The Scentometer, a small portable box device, has been in use since its development

in 195910

. The Scentometer, when used by an experienced technician, estimates the odor

concentration using a dilution threshold technique. Holes in the Scentometer box, specially sized,

allows ambient air to enter through charcoal filters and directly to the users sniffing ports. The

Scentometer, a single user device, is limited primarily by wind conditions that affects the air

entering the open holes in the sniffing chamber.

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Odor Persistence

Persistency is a term used in conjunction with intensity. The intensity of an odor will change in

relation to its concentration. However, the rate of change in intensity verses concentration is not

the same for all odors. This rate of change is termed the persistency of the odor.

The persistency of an odor can be measured in an odor laboratory as a dose-response function.The dose-response function is determined from the intensity of an odor at full strength and at

several dilution levels above the threshold level. The plotted values as logarithms of the intensity

and dilution ratios makeup the dose-response function. In a simplified form for comparing two

odors, i.e. odor with and without counteractant, the plots of the two samples might have different

slopes. As illustrated in Figure 1, the odor with the flatter slope would have a greater persistency,

i.e. greater Hang Time (slang) in the ambient air.

CONCLUSIONS

MSW landfill odor data collection and analysis address four basic questions:

1) Whatare the odors ? (Description)

2) Whenare the odors ? (Relation to time, activity, episode )

3) Whereare the odors ? (In the Community)

4) What does or does not causethe odors ? (Sources, activity )

MSW landfill odors can be quantified using ten (10) site specific methods(protocols) for sample

collection and direct observation.

1. Point Source Sampling

2. Surface Sampling

3. On-Site Monitoring4. Complaint Response

5. Random Monitoring

6. Scheduled Monitoring

7. Citizen Monitoring

8. Citizen Jury

9. Intensive Odor Study

10. Plume Profiling

Standard practices for odor quantification at MSW landfills include: characterization bydescriptors, intensity by word and butanol scales, threshold evaluation, and odor persistence.

MSW landfills have the opportunity to embrace standard methods and practices of odor

quantification for purposes of self improvement, survival and growth. Proactive odor

management strategies with ongoing monitoring and aggressive odor control will provide

assurances of favorable public acceptance, regulatory compliance and informed management

decision making.

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REFERENCES

1. Barboza, M.J., Municipal Solid Waste Landfill Gas Emissions,Air Pollution Engineering

Manual, Air & Waste Management Association, Van Nostrand Reinhold, pp863-874, 1992.

2. McGinley, D.L. and McGinley, M.A.; Understanding Odor Panels and Odor Evaluation,

Proceedings of the Air & Waste Management Association 90th

Annual Meeting andExhibition, Toronto, Ontario, Canada, 8-13 June 1997.

3. Reinhart, D.R. and Cooper, D.C.; Flux Chamber Design and Operation for the Measurement

of Municipal Solid Waste Landfill Gas Emission Rates,J. Air Waste Management

Association, 42:1067-1070, 1992.

4. Jiang, K. and Kaye, R.; Quantification of Odour Emission Sources at Wastewater Treatment

Plants, Proceedings of the Odors: Indoor and Environmental AirSpecialty Conference of

the Air & Waste Management Association, pp 407-414, Bloomington, Minnesota, 13-15

September, 1995.

5. Mallevialle, J. and Suffet, I.H. Editors,Identification and Treatment of Taste and Odors in

Drinking Water, American Water Works Association Research Foundation, p.107, 1987.

6. ASTM E544-89: Standard Practice for Suprathreshold Intensity Measurement,American

Society for Testing and Materials, Philadelphia, PA., 1989.

7. McGinley, C.M.; McGinley, D.L.; McGinley, K.J.; Curriculum Development for Training

Field Odor Investigators;Proceedings of the Odors: Indoor and Environmental Air

Specialty Conference of the Air & Waste Management Association, pp 121-130,

Bloomington, Minnesota, 13-15 September, 1995.

8. ASTM E679-91: Standard Practice for Determination of Odor and Taste Thresholds By a

Forced-Choice Ascending Concentration Series Method of Limits,American Society for

Testing and Materials, Philadelphia, PA., 1991.9. Scentometer: An Instrument for Field Odor Measurement, Barneby & Sutcliffe Corporation,

1974.

10. Huey, N.A.; Broering,L.C.; Jutze, G.A.; Gruber, C.W.; Objective Odor Pollution Control

Investigation,JAPCA, Vol. 10, No. 6, December 1960.

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Table 1. Grouping of Odor Descriptors for MSW Landfills.

Group 1: Earthy Mushroom Mouse-like

Musty Peat-like Chalk-like

Moldy Grassy Cork-like

Musk Herbal Bark-like

Stale Ashes Woody

Group 2: Floral Eucalyptus Carnation

Fragrant Geranium RoseFlowery Violet

Perfume Lavender

Group 3: Fruity Apple Vegetable

Citrus Pear Honey Dew

Orange Strawberry Cucumber

Lemon Pineapple Celery

Group 4: Spicy Garlic Vanilla

Cinnamon Onion Almond

Mint Pepper Maple

Peppermint Dill Pine

Anise Cloves Coconut

Group 5: Fishy Prawns/Shrimp Amine (hair perm

solution)

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Table 1 (cont.). Grouping of Odor Descriptors for MSW Landfills.

Group 6: Sewage Garbage Foul

Septic Rotten Sour

Putrid Decayed Vinegar

Rancid Raw Meat Pungent

Fecal Blood Burnt

Urine Cadaverous Swampy

Sulfurous Rotten Eggs Mercaptan

Group 7: Medicinal Chlorinous Alcohol

Disinfectant Soapy Ether

Phenol Caster Oil Anesthetic

Camphor Ammonia Menthol

Group 8: Chemical Petroleum Tar

Solvent Car Exhaust Oily

Paint Diesel Pine Oil

Aromatic Gasoline Plastic

Varnish Creosote Vinyl

Turpentine Kerosene Metallic

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Figure 1. Odor Persistence Illustrated.

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Log of

Intensity

Log of Dilution Ratio

Odor with Greater

Persistence

Odor with Less

Persistence

Documents

Odor Quantification MSW